Evolution Mostly Driven By Brawn, Not Brains

Evolution Mostly Driven By Brawn, Not Brains

The most common measure of intelligence in animals, brain size relative to body size, may not be as dependent on evolutionary selection on the brain as previously thought, according to a new analysis by scientists. Brain size relative to body size has been used by generations of scientists to predict an animal’s intelligence. For example, although the human brain is not the largest in the animal kingdom in terms of volume or mass, it is exceptionally large considering our moderate body mass.

Now, a study published in the Proceedings of the National Academy of Sciences has found that the relationship between the two traits is driven by different evolutionary mechanisms in different animals. Crucially, researchers have found that the most significant factor in determining relative brain size is often evolutionary pressure on body size, and not brain size.